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91.
Rashmi S. Kulkarni Nagendrappa Gopalpur Sowmya H. B. Vijaya Kumar Sunil S. More 《合成通讯》2014,44(3):331-339
The article describes a convenient and efficient synthetic route for the construction of 2-aroylbenzofuran-3-ols from readily available diverse methyl salicylates and phenacyl bromides using K2CO3 as catalyst in dimethylformamide as solvent at room temperature. The reaction involves two steps, which occur in quick succession within 1 h to deliver the product with reasonably high yields. All the synthesized 2-aroylbenzofuran-3-ols (4a–u) were subjected for their antimicrobial studies, and some of these have shown prominent activity.
[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.] 相似文献
92.
Ramesh M Raju B Srinivas R Sureshbabu VV Narendra N Vasantha B 《Journal of mass spectrometry : JMS》2010,45(12):1461-1472
Four pairs of positional isomers of ureidopeptides, FmocNH‐CH(R1)‐φ(NH‐CO‐NH)‐CH(R2)‐OY and FmocNH‐CH(R2)‐φ(NH‐CO‐NH)‐CH(R1)‐OY (Fmoc = [(9‐fluorenyl methyl)oxy]carbonyl; R1 = H, alkyl; R2 = alkyl, H and Y = CH3/H), have been characterized and differentiated by both positive and negative ion electrospray ionization (ESI) ion‐trap tandem mass spectrometry (MS/MS). The major fragmentation noticed in MS/MS of all these compounds is due to ? N? CH(R)? N? bond cleavage to form the characteristic N‐ and C‐terminus fragment ions. The protonated ureidopeptide acids derived from glycine at the N‐terminus form protonated (9H‐fluoren‐9‐yl)methyl carbamate ion at m/z 240 which is absent for the corresponding esters. Another interesting fragmentation noticed in ureidopeptides derived from glycine at the N‐terminus is an unusual loss of 61 units from an intermediate fragment ion FmocNH = CH2+ (m/z 252). A mechanism involving an ion‐neutral complex and a direct loss of NH3 and CO2 is proposed for this process. Whereas ureidopeptides derived from alanine, leucine and phenylalanine at the N‐terminus eliminate CO2 followed by corresponding imine to form (9H‐fluoren‐9‐yl)methyl cation (C14H11+) from FmocNH = CHR+. In addition, characteristic immonium ions are also observed. The deprotonated ureidopeptide acids dissociate differently from the protonated ureidopeptides. The [M ? H]? ions of ureidopeptide acids undergo a McLafferty‐type rearrangement followed by the loss of CO2 to form an abundant [M ? H ? Fmoc + H]? which is absent for protonated ureidopeptides. Thus, the present study provides information on mass spectral characterization of ureidopeptides and distinguishes the positional isomers. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
93.
Sayan Shee Sowmya Shree Ranganathappa Mahesh S. Gadhave Romin Gogoi Prof. Dr. Akkattu T. Biju 《Angewandte Chemie (International ed. in English)》2023,62(52):e202311709
Axially chiral diaryl ethers, a distinguished class of atropisomers possessing unique dual C−O axis, hold immense potential for diverse research domains. In contrast to the catalytic enantioselective synthesis of conventional single axis bearing atropisomers, the atroposelective synthesis of axially chiral ethers containing flexible C−O axis remains a significant challenge. Herein, we demonstrate the first N-heterocyclic carbene (NHC)-catalyzed synthesis of axially chiral diaryl ethers via atroposelective esterification of dialdehyde-containing diaryl ethers. Mechanistically, the reaction proceeds via NHC-catalyzed desymmetrization strategy to afford the corresponding axially chiral diaryl ether atropisomers in good yields and high enantioselectivities under mild conditions. The derivatization of the synthesized product expands the utility of present strategy via access to a library of C−O axially chiral compounds. The temperature dependency and preliminary investigations on the racemization barrier of C−O bonds are also presented. 相似文献
94.
Sowmya G. Gireesha B. J. Animasaun I. L. Shah Nehad Ali 《Journal of Thermal Analysis and Calorimetry》2021,144(6):2369-2384
Journal of Thermal Analysis and Calorimetry - During the production of iron(iii) oxide and silver nanoparticles where water is inevitable, little is known on the transport phenomenon in a... 相似文献
95.
In this study, gold microelectrode array (Au/MEA) with electrode of 12 μm diameter was fabricated by photolithography technique. Subsequently, polypyrrole (Ppy) modified gold microarrays sensor (Ppy/Au/MEA) was prepared by cyclic voltammetry technique. The deposition potential range and number of cycles were optimised in order to get optimum thickness of Ppy film. Scanning Electron Microscope and Atomic Force Microscope investigations reveal that Ppy coating formed at 3 cycles is porous with thickness of 1.5 μm which exhibiting high catalytic current for ascorbic acid (AA) in square wave technique (SWV). In contrast to earlier sensors designs, these Ppy/Au/MEA sensors exhibits lower detection limit (LOD) of 10 nm towards AA at physiological conditions. It also exhibits enhanced sensitivity (2.5 mA cm−2 mM−1) and long range of linear detection limit from 10 nm to 2.8 mM. In the same way, polypyrrole modified macro Au (Ppy/Au/MA) biosensor was also fabricated and its electro catalytic property towards AA was compared with that of Ppy/Au/MEA. The Ppy/Au/MA exhibits sensitivity of only 0.27 mA cm−2 mM−1, LOD of 5 μM and linear range of 10 μM to 2.2 mM. Hence, our investigations indicate that the Ppy/Au/MEA could serve as highly sensitive sensor for AA than any of the earlier designs. So, the Ppy/Au/MEA electrode was utilised for determination AA in a wide variety of real samples. 相似文献
96.
Subhashini Naikal James Prameela Lavanya Jilla Sowmya Vanguru 《Journal of heterocyclic chemistry》2020,57(1):308-316
A new series of benzosuberone-piperazine hybrids 6a to j were designed and synthesized efficiently in good yields and their structures were confirmed by 1H NMR, 13C NMR, ESI-MS and HRMS. The newly synthesized compounds were evaluated for their in vitro antimicrobial activity against Gram positive, Gram negative bacterial strains and a fungal strain. Among the synthesized compounds, compounds 6c , 6d , 6e , 6f , 6g and 6h exhibited potent antibacterial activity with MIC value of 1.9 μg/mL against Gram positive and Gram negative organisms. 相似文献
97.
Isolation and characterisation of compounds, 1-(2′-hydroxy-4′-methoxyphenyl)-3-(4″-methoxyphenyl)-2-hydroxypropane-1,3-dione (1), 5-hydroxyflavone (2), 3,5,7,3′,4′-pentahydroxyflavone (3), 3,5,7,2′,4′-pentahydroxyflavone (4) and 5,7,3′,4′-tetrahydroxyflavone-3-O-rhamnoside (5) are reported from the air dried flowering buds of Bauhinia tomentosa Linn. Their structures are determined on the basis of extensive chemical and spectral evidences. Compound (1) is reported for the first time from the plant source. While compounds (2) and (4) are reported for the first time from this genus, compound (2) is reported for the second time from the natural source. 相似文献
98.
Kamala L. Veena B. S. Anantha Lakshmi P. V. Vasantha P. Sujatha E. 《Russian Journal of General Chemistry》2017,87(2):316-321
Russian Journal of General Chemistry - 5-[(1H-Indol-3-yl)methylene]thiazolidine-2,4-dione–[1,2,3]triazole hybrid derivatives were synthesized by click chemistry reaction and screened for... 相似文献
99.
Conventional extraction methods of proanthocyanidins (PAC) are based on toxic organic solvents, which can raise concerns about the use of extracts in supplemented food and nutraceuticals. Thus, a PAC extraction method was developed for grape seeds (GS) and grape seed powder using food-grade ethanol by optimizing the extraction conditions to generate the maximum yield of PAC. Extraction parameters, % ethanol, solvent: solid (s:s) ratio, sonication time, and temperature were optimized by the central composite design of the response surface method. The yields of PAC under different extraction conditions were quantified by the methylcellulose precipitable tannin assay. The final optimum conditions were 47% ethanol, 10:1 s:s ratio (v:w), 53 min sonication time, and 60 °C extraction temperature. High-performance liquid chromatography analysis revealed the presence of catechin, procyanidin B2, oligomeric and polymeric PAC in the grape seed-proanthocyanidin extracts (GS-PAC). GS-PAC significantly reduced reactive oxygen species and lipid accumulation in the palmitic-acid-induced mouse hepatocytes (AML12) model of steatosis. About 50% of the PAC of the GS was found to be retained in the by-product of wine fermentation. Therefore, the developed ethanol-based extraction method is suitable to produce PAC-rich functional ingredients from grape by-products to be used in supplemented food and nutraceuticals. 相似文献
100.
Roddam Narasimha Srikanta Sastry Vasantha 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1966,17(5):585-592
Zusammenfassung Das Problem der Laminarströmung einer kompressiblen Flüssigkeit längs einer ebenen Platte bei grossen Prandtlzahlen wird mit Hilfe der Methode der inneren und äusseren Expansion gelöst unter der Annahme, dass das Produkt aus Dichte und Viskosität quer zur Grenzschicht konstant ist. Die Tabellen des Anhanges ermöglichen die Berechnung einer vollständigen Temperaturverteilung in der Grenzschicht für isolierte und nichtadiabatische Wände. Es erweist sich, dass die für den Rückgewinnungsfaktor gewonnene Formelr=1,922
1/3–1,341 eine wesentliche Verbesserung gegenüber früheren Ergebnissen ist, selbst bei =103. Es wird eine Interpolationsformel vorgeschlagen, die in die exakte asymptotische Lösung bei grossem übergeht und beir=1 ebenfalls =1 ergibt. 相似文献